gastell



'sepL 24, 1929. F. GASTELL 1,729,577

BLAST NOZZLE Filed June l5, 1928 lnrenfar jij-ff Patented Sept. 24, 1929UNlTED STATES PATENT FFICE BLAST NOZZLE Application filed June l5, 1928,Serial No. 285,671, and in Germany June 21, 1926.

The subject matter of the present invention is a nozzle or blast-pipearrangement, and a method of working; the same, for blowers or blastapparatus of the kind in which the materials to be blown out or sprayed,such as sand, steel balls` concrete masses, met-a1 etc., areI carriedforward, by the action of a stream of compressed air. gas, steam or thelike moving' forwards with great speed in a. tube or lo pipe, asconstituents to be mixed with the stream of air. steam or `ras expandingat the outlet end of the nozzle, and thereby perform work.

Hitherto, the mixture of compressed jras and materials to be blown orsprayed out has frequently been moved forwards in a nozzlebody whichnarrows continuously toward the outlet openingr and is oftencylindrical, and separate nozzle tubes of conical or cylindrical formfor conducting the gas and the materials to be blown out have onlyseldom been employed. In the former case the Wear on the nozzle isgreat, and in both cases the speed of the stream of the mixture of gasand materials to be sprayed out or of the gas alone lowing;` through thenozzle passages decreased greatly as it approached the outlet opening,so that the maximum attainable outlet speed of the blast could not beusefully :o employed. These disadvantages increased to such an extent atgas pressure exceeding two atmospheres that the employment of gaspressures exceeding the aforesaid maximum ressure was precluded to agreat extent rom 5 reasons of economy. If for special reasons highpressures above two atmospheres had to be employed this was done only inexceptional eases. Nevertheless an increase of pressure would bepreferable for many rea- 0 sons, if the results obtained were on asimilar sca-le to those obtained with pressures below two atmosphereswith respect to increased performance and wear on the nozzle.

The object of the present invention is to 5 solve this problem, whilemaintaining separate passages for the conduction forward of thecompressed gas and materials t0 be sprayed out which only unite at theoutlet where they are co-axial, by continuously wid- J ening the gaspassage towards the outlet opening, so that the cross-sectional. area ofthe passage and thereby the speed of the air or gas and with it thespraying,r effect continuously increases, that is to say the action issimilar to that of the de Laval nozzle.

A nozzle for carryingr out the aforesaid method of operation isillustrated by way of example in the accompanying drawing.

Referring to the drawing, the pipe l serves for the conduction ofcompressed air and the pipe 2 for the conduction of sand from anysuitably arranged vessel. The pipe l runs at the back of the device atan angle to the pipe 2. It is then formed with a bend and provided witha threaded {la-nge 3, which serves for the reception of the pipe 2, andruns further forwards co-axially with the pipe 2 which it then encases.The cross section of the free annular space between the two tubesincreases continuously towards the front from a narrowest part l, sothat the air passage is greatest at the outlet end like a de Lavalnozzle.

The sand fiowing through the tube 2 reaches the outlet 4 owing to thesuction of the escaping stream of air and is thence carried along by theescaping air with a speed which corresponds to the full pressure of theair.

It is known'that, owing to the widening from I to II the effect of thepressure prevailing in the tube l is increased, in so far as the speedof the air at the outlet l is considerably above the normal speed, thespraying effect which depends on the square of the outlet speed istherefore considerably increased.

By means ofthe new arrangement the airpressure is fully utilized, andany wearing out on the nozzles, pipes or other parts is eliminated. Thenew implement can be'used for similar processes in which, as in sprayingwith mortar, cement, metal, or even with acids, colours or the like, theadvantages of the new process can be utilized;

What I claim is A blast nozzle for blowing apparatus in which solidmaterials such as sand, steel balls, concrete masses, metal and the likeare sprayed by the suction of a compressed fluid,

comprising a tubular member for conveyin the solid materials to thenozzle outlet, an a. tubular member for conve ing the compressed iluidto the nozzle out et, said second tubular member approaching thefirst-mentioned tubular member at an an le and gradually curving intoparallelism t erewith, and enclosing the first-mentioned tubular member,along the parallel part thereof, with an annular gap between, the innertubular member which conveys the solid material, at flrst increasino inwall thickness from the place at which the wall of the outer tubularmember, which conveys the compressed fluid, becomes parallel thereto,andboth tubular members uniformly decreasing in wall thickness over thelatter part of their length, without any alteration occurring in theexternal diameter of the outer tubular member or in the internaldiameter of the inner tubular member.

` In testimony whereof I have signed my name to this specication.

. FRANZ GASTELL.

